Due to the recent development of the information/communication technology, network devices such as base stations are installed everywhere, and an electronic device may allow the user to freely use networks everywhere, by transmitting and receiving data to and from another device through the networks.
An antenna is necessary to use the networks. With the development of the information/communication technology, the antenna technology also has developed, and in recent years, studies for efficiently securing an arrangement space for an antenna of elements of an electronic device, which is provided for communication, and preventing lowering of radiation performance of the antenna in advance have been made.
The antenna used in the electronic device may include an inverted-F antenna (IFA) or a monopole radiator as a basic structure, and the volumes and the number of mounted antenna radiators may be changed according to the frequencies to be serviced, the bandwidth, and the type of the antenna. For example, frequencies may be different for regions, but generally, a low band of about 700 MHz to about 990 MHz, a mid band of about 1700 MHz to about 2100 MHz, and a high band of about 2300 MHz to about 2700 MHz may be used as main communication bands. Further, various communication services such as BLUETOOTH (BT), Global Positioning System (GPS), or Wi-Fi are being used, but is it difficult to design one antenna that supports all the aforementioned communication bands in a limited volume of the electronic device.
Meanwhile, in a European product, it is necessary for an antenna to support at least 24 bands such as 2nd generation (2G) (Global System for Mobile Communications (GSM) 850 MHz (GSM850), extended GSM (EGSM), Digital Cellular System (DCS), and Personal Communications Service (PCS)), Wideband Code Division Multiple Access (WCDMA) (B1, B2, B5, and B8) and long term evolution (LTE) (B1, B2, B3, B4, B5, B7, B8, B12, B17, B18, B19, B20, B26, B38, B39, B40, and B41). Because it is difficult to satisfy specifications required by the communication businesses and also satisfy specific absorption rate (SAR) standards while realizing the bands with one antenna, at least two service bands having close frequency bands may be combined to implement an antenna. For example, it may be designed such that one antenna supports 2G (GSM850, EGSM, DCS, and PCS), WCDMA (B1, B2, B5, and B8) and LTE (B1, B2, B3, B4, B5, B8, B12, B17, B18, B19, B20, B26, and B39) and another antenna supports LTE (B7, B38, B40, and B41).
Generally, in order that two antennas may be operated in different bands, the two antennas should be designed such that electric power is fed to the antennas by using different radio frequency (RF) ports (feeders) and a specific isolation or more is secured between the two antennas to minimize mutual influence.
For example, one antenna may be disposed at the left end of the electronic device, and another antenna may be disposed at the right end of the electronic device. In this case, if it is designed such that different antennas support a low band (for example, B20, B8, B17, or the like), it is difficult to secure an isolation of λ/4 or more that is a minimum distance by which an isolation may be secured, when it is considered that the width of a general electronic device (for example, a smartphone) is about 70 mm to 80 mm (λ/4 of a low band (for example, 900 MHz is about 80 mm). Meanwhile, because a low band may be secured by a switching technology, one antenna is implemented by a penta-band antenna that supports a low band, and another antenna may be implemented by an antenna that supports a high band such as LTE B7, B38, B40, or B41. However, in this case, because the length of the antenna is short, the performance of the antenna may be lowered by an influence of the human body when the electronic device is gripped by a hand of the user.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.